Gelatin-base coating for food and the like



food products, food cartons, carton stock, and fore have provided coatings serving as good culbeen a practical and successful protecting agent. film strength when set. i In most instances, however, when gelatin has been It is a particular object to provide gelatinused in a hot bath there has been a loss in gelatin 3:, oated meat or meat products, such as hams, strength due to hydrolysis of the gelatin material which can be stored for long periods at the usual i in solution form. Because gelatin is a good culcold storage temperatures just above 32 F. C.)

ture medium for yeasts, molds and bacteria, these without danger of unsightly change in the gelatin y readily ow in and on the gelatin coating, coat by the growth of mold, yeast or bacteria.

atentedl Aug. Q, 1949 GlEiLA'llllN -1BASE COATING ]F OR FOOD AND THE LIKE lLloydl A. Hall, Chicago, 11]., assignor to The Grifflth Laboratories, inc, Chicago, 11]., a corporation of Illinois No Drawing. Application March l, 1945, Serial No. 580,477

8 Claims. (Cl. 99-166) i This invention relates to protective coatings and fly-sting, and readily huskable from the and particularly to edible coatings to be used on article coated. foodstuiis such as meats, fruits, vegetables, other Gelatin-base coating compositions used heretoother articles and materials used in the food ture media for yeasts, mold and bacteria. Also,

industry, in practical use of such compositions, it has been The problem of coating food materials, in parimpossible to hold-over dipping baths of such ticular meats, such as hams, butts, sausage, bacon, compositions, as from use on one day to use on the baked wares, and packaged fatty products like next day, because the first day's use contaminates lard, butter and margarine, has received much at- 10 the bath with micro-organisms, which multiply tention, primarily due to the increased demands therein overnight. To hold such baths at a sterfor sanitary products for storage and for shop llizing heat, effects degredation of the gelatin display, and also because of import and export therein, thereby impairing the coating of its next trade calling for protection against severe changes use, and limiting the time of use of the bath. The in climatic conditions, exposure to flies, insects, impairment lowers the viscosity, which should be micro-organisms, dirt, and other factors. high for forming a good coating by dipping.

Although there is a large number of materials The present invention overcomes all these difilwhich are available for coating food products, culties and provides a gelatin bath and coat,

there are serious practical and conflicting restricwhich inhibit the growth of infecting micro-ortions against their use. Waxes, in particular, ganisms, such as yeasts, molds and bacteria, parafiin wax and other'commercial waxes, have which resists degradation by heating; and which been used for coating for many years. These can be used for numerous reheatings over a pro waxes are not edible. They have not been satislonged period of time.

factory because they are not entirely impervious It is the general object of my invention to proto air and are subject to breaking and cracking vide an improved gelatin-base coating.

in handling and transporting. They are also It is a particular object of the invention to subject to crumbling and breaking away from the provide a gelatin-base coating which is resistant foods on cutting or slicing, and constitute, thereto micro-organisms.

fore, a unsuspected danger of food contamina- It is also an object to provide a gelatin-base tion with the coating material. coating material which can be set and remelted Gelatin has been used as a coating material numerous times without loss of its viscosity charfor food products and in certain instances has acteristics when melted and without loss of its making it as objectionable as if the fOOd product Numerous other and ancillary object and adhad not beef} c d at Because of vantages of the invention will appear from the Federal restrictions, it has heretofore not been f ll wi g description and explanation of the permitted in the United States to treat a gelatin ventiom coating on food products with certain suitable Gelatin by itself provides a rather brittle coatchemicals to make it mold and bacteria proof, or, to use certain well known chemicals to harden the a to avold this qp ii of gelatin, all of which are undesirable, and many of g i i has i glvmg fiexlbmty and which are toxic elasticity. In said prior Patent No. 1,914,35 20 According to Patent 1,914,351 in parts of glycerine were used to 100 parts of gela- Which the present applicant is a jomnpatenteey tin to produce a flexible elastic adherent film adthere was developed a iairly satisfactory protec-, jacent food, Such as thesurface of a tive coating using gelatin. This patent described e s usage of elycerine is known with correa procedure wherein foodstufis were coated by a sponding lessening of its plasticizing efiect- But dipping process to form a multi-layer skin coating even with 20% of glycerine, itwas necessary to which was impervious to atmospheric conditions add a sterilizing agent to avoid mold growth on I 3 coated articles, or mold growth in a dipping bath held overnight.

I have discovered that when propylene glycol is used in a gelatin composition at and above a certain content, a gelatin-film-forming composition and resulting film or coat may be made, which are resistant to the growth of infecting yeasts, molds and bacteria. Propylene glycol is,

as of this date, permitted by U. S. Federal reguabout 15% by weight. I have determined that a content of about 15% by weight of propylene glycol is the lower critical limit for inhibition of microorganisms. An upper limit of about 20% content of propylene glycol is not critical as to said inhibition, but is imposed only because of undesired physical effects for the present invention. When more than about 20% by weight of propylene glycol is present, the gelatin film or coat is too soft for the conditions to which it is designed to be subj cted.

Thus, a desirable film-coating for food and food packages becomes available. The resistance of the bath composition to damage by supporting the growth of yeasts, molds or bacteria, permits the bath to be used'over and over; but to avoid degradation of the bath by such hold-over use, it is made resistant to degradation by heat, as another feature of the present invention, by adjustment of its pH. Useful grades of gelatin have normal pH values ranging from 4.0 to 5.5. This acidity initiates and accelerates degradation in heating unbuifered fluid aqueous gelatin compositions. Acidity is increased by such degradation. I have found that by suitable adjustment of the pH to neutrality or just below it, as in the range from pH 6.5 to 7, the composition is stable for long periods, without losing its desired viscosity characteristics, when maintained heated to a coating fluidity, or when numerous times cooled to set it and reheated to liquify it. A composition adjusted to a pH in the range of 6.5 to 7 and containing said minimum effective quantity of propylene glycol, exhibits the desired resistance'to the growth of yeasts, molds and bacteria. Many neutralizing or buffering agents may be used, including soluble ones and even insoluble ones, such as insoluble calcium carbonate. However, for food products, edible and soluble neutralizing or buffering agents are preferred, such as alkanol amines, preferably triethanol amine, sodium carbonate, sodium bicarbonate and disodium phosphate.

Triethanolamine is preferred to inorganic agents. It is not a strong electrolyte, and it does not impart ash content to the coating. It is less likely to migrate from the coating in contact with moist food, such as meat.

Reducing sugar may be employed in the composition as a protective agent, particularly to act as an anti-oxidant for gelatin. Where the composition as a bath may be reheated numerous times, as described, there is a tendency for oxidation of gelatin to occur, producing an acid condition. Although the presence of the buflering agent will counteract such acid, it is preferred to minimize the amount of such buflering agent by providing such anti-oxidant. Too much sugar (over about 10%) causes tackiness in the film. Up to a content of 10%, the reducing sugar does not interfere with the characteristics of nontackiness, viscosity, keeping, or resistance to growth of microorganisms. Forms of sugar containing trace impurities of acid, such as commercial grades of corn sugar, may be used without danger to the gelatin, when alkaline agent, neutralizing agent, or buffering agent is present. Suitable reducing sugars are dextrose, lactose, and maltose. Sugar may be omitted if desired, and especially where the composition is used in a manner not subjecting the gelatin content to prolonged heating, as for example, when coatin carton stock. In such practice dipping baths are not commonly required and hence are not held over and remelted.

Gelatin is available in numerous grades commercial-1y containing from 8% to 10% of water content. Edible gelatin varies in grade by a Bloom number, being commonly in the range from 125 to 300 Bloom. The lower the Bloom 7 number, the softer the gel formed by it and the less viscous a solution of it. Thus, the higher the Bloom number, the less gelatin and the more water, which may be used in preparing the compositions. The liquid compositions of the present invention are such as to provide one which sets on cooling and liquifies on heating, with little loss of water from the set composition.

In the following examples. parts are given by weight.

Example 1 2 3 4 5 Edible Gelatin (zoo Bloom) 32 32 32 a2 Edible Gelatin (250 Bloom) 30 Dextrose (or other Reducing 4 4 4 4 4 20 1s 1s 16 15 1 1 1 1 Water Tap- H5.8to6) 48.7 54.1 458 356' pH.. .S as 7.0 6.5 6.8 as

In the above examples, the propylene glycol is respectively 19%, 16.8%, 17.3%, 15.5% and 14.3% of the ingredients listed. However, in large batches where the parts given are in pounds, there is during the time of processing, an evaporation of water. Example 1, yields 100 lbs. of liquid composition. Water may be added as necessary, or evaporated, or the amount varied, so long as the content of propylene glycol is maintained, to provide about or substantially 15% or more by weight. Thus, Example 5 has only 14.3% of propylene glycol in the ingredients I listed, but the loss of about 5 parts of water gives approximately 15% content of propylene glycol in the composition to be used.

The neutralizing, buffering or alkaline agent is added in quantity to give a pH in the range y from 6.5 to 7.

water is either 37.8% or 37%. These are the extremes of the disclosures in Examples 1 to 5 with respect to the ratio of gelatin to water. In general these proportions fall within a range of 170 to 215 parts by weight of water to parts of 100%- dry gelatin.

In making the composition, the gelatin and propylene glycol are made into a substantially uniform mixture. The water, pH controlling agent, and any dextrose or the like, are made into one solution, which is added to the mix of gelatin and propylene glycol. The mass is heated in a steam or hot-water jacketed kettle to a temperature in the range from 140 to 155 F., until fluid, transparent and uniform. Agitation forming froth is avoided to keep bubbles of air out of the mix.

The mixture cooled from this temperature sets. On heating it melts. Thus, articles may be dipped in the hot bath at 140 to 155 F., drained and cooled. The viscosity of the fluid is such as to form a suitable heavy film, on a ham for instance. By limiting the prevailing temperature to 140 to 155 F., the mixture may be cooled and heated many times, over a period of 60 days, without loss of a desirable film-forming viscosity. Of course, for short periods, the mixture may be at higher temperatures, but for substantial safety over long periods to time, 155 F. is recommended as an upper limit.

With respect to the composition of Example 1, the following comparisons evidence the value of the invention.

(1) Over a period of 30 days, the composition was remelted every day at 140 to 150 F., and the viscosity (Stormer) varied from 165.4 to 128. A like composition without the triethanolamine similarly treated changed in viscosity from 73.4 to 28.6.

(2) The composition was inoculated by adding some paprika having a count of 68,533,000 bacteria per gram, and a count of 105 yeast and mold spores per gram. When the thus-infected gelatin composition was incubated at 55, 37 and 0 0., no colonies of yeasts, or of molds, or of bacteria developed.

(3) Into a coating solution at 120 F. (49 C.)'

was added black pepper having a count of 42,566,000 bacteria per gram, and a count of 230 of yeasts and molds per gram. This was incubated at 37 C., and at 0 developed.

(4) Hams dipped into the composition were hung at 38 to 40 F. for four months without developing yeast or mold growth on the surface, thus presenting a clean and saleable appearance.

(5) Duplication of the composition and tests 1, 2, 3 and 4, above, omitting the propylene glycol, produced heavy colonies of yeasts, molds and bacteria in each instance. Also, like compositions with only 10% and 12 by weight of propylene glycol, incubated at 0 and 37 0., gave abundant growth of mold, obscuring the test plates for bacteria counts. The growth at 12 was less than at 10%.

The composition as a coating has been in contact with contaminating'foods, such as meats and sausage, for as long as six months, while C., and no colonies retaining its property of inhibiting the growth of microorganisms.

The composition is resistant to oils, fats and greases, and serves as an excellent coating for paper and carton stock, for cheese, lard, butter, margarine and like fatty foods. Being elastic, it is an improvement over wax in such uses, as it does not crack or peel, and therefore, resists transmission not only of fat in one direction, but of contaminationin both directions.

It is to be appreciated that the desirable high viscosity is pertinent to use in dipping operations. Where coating operations of a difierent sort,

as by a coating roller on paper stock, are used, high viscosity is not so important. 1 In such cases, the pH-controlling agent may be omitted, and the solution prepared as quickly as possible to minim'ze degradation. The reducing sugar may be omitted also in this circumstance, as well as in cases where the pH is adjusted to 6.5 to 7.

Numerous variations in compositions and uses may be practiced without departing from the spirit and scope of the invention as expressed in the appended claims.

I claim:

1. A coating composition for association with foods and packages therefor, comprising essentially water and edible food gelatin in the proportion by weight of 170 to 215 parts of water to parts of 100%-dry gelatin, a pH-controlling agent, and propylene glycol, said composition being normally solid but liquid at a temperature in-the range from to F., and being characterized on cooling a liquid coat thereof by setting to a plastic film having from about 15% to about 20% by weight of propylene glycol, the content of pH-controlling agent being such as to impart to said film a pH in the range from 6.5 to 7.

2. A coating composition for association with foods and packages therefor, comprising essentially water and edible food gelatin in the proportion by weight of to 215 parts of water to 100 parts of 100%-dry gelatin, a pH-controlling agent,. a water-soluble reducing sugar, and propylene glycol, said composition being normally solid but liquid at a temperature in the range from 140 to 155 F., and being characterized on cooling a liquid coat thereof by setting to a plastic film having from about 15% to about 20% by weight of propylene glycol, controlling agent being such as to impart to said film a pH in the range from 6.5 to 7.

3. A non-tacky adherent film composition comprising waterand gelatin in the proportion by weight of 170 to 215 parts of water to 100 parts of 100%-dry gelatin, a pH-controlling agent, and

propylene glycol, the latter being present in quantity from about 15% to about 20% by weight, and the composition having a pH in the range from 6.5 to 7.

4. A non-tacky adherent film composition comprisingwater and gelatin in the proportion by weight of 170 to 215 parts of water to 100 parts of 100%-dry gelatin, a pH-controlling agent, water-soluble reducing sugar, and propylene glycol, the latter being present in quantity from about 15% to about 20% by weight, and the composition having a pH in the range from 6.5 to 7, the sugar being limited in quantity to avoid tackiness of the composition.

5. A coating composition for association with foods and packages therefor, comprising essentially water and edible food gelatin in the proportion by weight of 170 to 215 parts of water to 100 parts of 100%-dry gelatin,,and propylene glycol,

said composition being normally solid but liquid at a temperature in the range from 140 to 155 F., and being characterized on cooling a liquid coat thereof by setting to a plastic film having about 15% to about 20% by weight of propylene glycol.

6. A gelatin-base composition having in gelfilm form and by weight from 1'70 to 215 parts of water to 100 parts of 100%-dry gelatin, and from about 15% to about 20% of propylene glycol, and characterized by inhibition of the growth of microorganisms at temperatures above 0 C.

7. A gelatin-base composition having by weight the content of pH a 7 from 1'10 to 215 parts of water to 100 parts of 100%-dry gelatin, and from about 15% to about 20% of propylene glycol, and characterized by inhibition of the growth of microorganisms at temperatures above 0 C. a

8. A liquid coating composition for food and food materials, which comprises a solution of edible gelatin in water having a content of water quent loss of suitable viscosity for coating, and may be alternately heated and cooled without danger of supporting growth of yeasts, molds and bacteria.

LLOYD A. HALL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,148,823 Bocande Aug. 3, 1915 1,853,151 Segur et al. Apr. 12, 1932 1,914,351 Hall et al. June 13, 1933 2,021,137 Stone Nov. 19, 1935 2,051,170 Helfrich Aug. 18, 1936 2,333,124 Robertson et al Nov. 2, 1943 

